Electrolytic reductive coupling of activated olefins



Patented May 3, 1966 3,249,521 ELECTROLYTIC REDUCTIVE CGUPLING F ACTIVATED GLEFINS Manuel M. Baizer, St. Louis, Mo., assignor to Monsanto Company, a corporation of Delaware No Drawing. Filed Jan. 31, 1963, Ser. No. 255,221 14 Claims. (Cl. 20473) This invention relates to the manufacture of polyfunctional compounds and more particularly provides a new electrolytic process for reductively coupling alpha, betaolefinic phosphonates, phosphinates, phosphine oxides and sulfones.

An object of the invention is the provision of a process for the preparation of bis-phosphonates, bis-phosphinates, bis-phosphine oxides and bis-sulfones.

The process can be illustrated by the following equation:

where Z is PO(OR) P(O)R(OR), P(O)R or S0 and the Rs are individually selected hydrocarbyl radicals. The Rs can be any inert, monovalent, preferably hydrocarbon, radicals, as such as alkyl, cycloalkyl, aralkyl, aryl, etc., radicals.

The process is further illustrated:

Ill HRRH where the Xs are individually selected from the group consisting of R and OR and the R"s are individual hydrocarbyl radicals while the Rs are individually selected from hydrocarbyl radicals and hydrogen. The R"s and Rs can be such hydrocarbyl radicals as alkyl, aryl, aralkyl, alkaryl, cycloalkyl, etc., radicals, for example, methyl, ethyl, propyl, isopropyl, butyl, amyls, hexyls, phenyl, tolyl, xylyl, benzyl, phenylethyl, etc., and the Rs can also be hydrogen. While the radicals can have up to 20 or more carbon atoms, it is preferred that they contain no more than carbon atoms, and also that they contain no non-benzenoid unsaturation, i.e., that they be saturated except for the unsaturation in the aryl rings. Ordinarily the aryl groups will be monocyclic, although various polycyclic radicals, e.g., naphthyl, anthracyl, etc., are also applicable. The hydrocarbyl radicals, can, if desired, contain relatively inert, non-interfering substituents.

The process for the alphabeta-unsaturate d sulfones can be suitably illustrated by substituting S0 for P(O)X in the above equation, and defining R as immediately above.

Various specific compounds which can be reductively coupled according to the present process are diethyl vinylphosphonate, ethyl ethylvinylphosphinate, diethylvinylphosphine oxide, diphenylvinylphosphine oxide, methyl vinyl sulfone, ethyl vinyl sulfone, diphenyl vinylphosphonate, ethyl, phenyl vinylphosphonate, ethyl, hexyl vinylphosphonate, hexyl ethylvinylphosphinate, phenyl methylvinylphosphinate, ethyl phenylvinylphosphinate, l-propenyl methyl sulfone, diethyl l-propenylphosphonate, diethyl styrylphosphonate, ethyl ethyl-Lpropenylphosphinate, diphenyl-l-propenylphosphine oxide, diphenylstyrylphosphine oxide, phenyl styryl sulfone, phenyl vinyl sulfone, etc.

The process is of particular interest for reductive coupling of vinylene phosphonates, phosphinates, phosphine oxides and sulfones, ordinarily with vinylene groups of up to 8 carbon atoms, particularly with such l-alkenyl groups.

In accordance with the above equations, each of the foregoing compounds is reductively coupled, i.e., hydrodimerized, by the electrolysis process of the present invention to obtain the corresponding bis-phosphonate, bisphosphinate, bis-phosphine oxide or bis-sulfone. The compounds can also be reductively coupled in various combinations to produce various types of cross-coupled compounds, or, if desired, reductively coupled in combination with various other types of alpha,beta-olefinic compounds capable of reductive coupling, e.g., alpha,betaolefinic nitriles, esters or amides, to produce various other types of cross-coupled compounds.

In general, the electrolytic reductive coupling of the present invention is conducted in concentrated solution in an aqueous electrolyte. It is desirable to employ fairly concentrated solutions in order to minimize undesired reactions of intermediate ions with the water of the electrolyte. The olefinic reactants will ordinarily comprise at least about 10% by weight of the electrolyte, and preferably at least 20% by weight or more. It is generally desirable to employ fairly high concentrations of salts in the electrolyte, for example constituting 5% and usually 30% or more by weight of the total amount of salt and water in the electrolyte, in order to obtain the desired solubility of the olefinic compounds. It is often desirable to utilize co-solvents such as acetonitrile or dimethylformamide to improve solubility of the olefinic reactant.

The hydrodimerization of alpha,beta-olefinic carboxylates, nitriles and carboxamides is taught in my copending applications S.N. 145,480 and 145,482, filed October 16, 1961, and SN. 75,130, filed December 12, 1960, the disclosures of which are incorporated herein by reference; the foregoing applications have now been abandoned in favor of continuation-impart applications S.N. 333,647, filed December 26, 1963, and issued July 6, 1965, as Patent No. 3,193,481, S.N. 337,540, filed January 14,

1964, and issued July 6, 1965, as Patent No. 3,193,482,.

and SN. 337,546, filed January 14, 1964, and issued July 6, 1965 as Patent No. 3,193,483. The conditions taught in the referred-to applications [for hydrodimerization are suitable for hydrodimerization or other reductive couplings of the present invention.

Electrolysis, of course, has been practiced for many years and numerous materials suitable as electrolytes are known, making it within the skill of the art in the light of the present disclosure to select electrolytes for reductive coupling according to the present invention. The use of excessively acidic or excessively alkaline conditions may cause undesirable side reactions, and the use of acidic conditions also tends to utilize current in the production of hydrogen; to minimize such factors, the pH is usually maintained in the range of about 5 to about 12, preferably about 6 to 9.5. Slightly alkaline solutions are conveniently employed.

When the catholyte during electrolysis is acidic, it may be advisable to conduct the electrolysis under conditions which inhibit polymerization of the reactants involved or in the presence of a polymerization inhibitor, for example, in an atmosphere containing sufiicient oxygen to inhibit the polymerization in question, or in the presence of inhibitors effective for inhibiting free radical polymerization. Classes of inhibitors for inhibiting free radical polymerizations are well known, e.g., such inhibitors as hydroquinone, p,t-butyl catechol, quinone, pnitroso dimethylaniline, di-t-butyl hydroquinone, 2,5-dihydroxy-1,4-benzoquinone, 1,4-naphthoquinone, chloranil, 9,10-phenanthraquinone, 4-amino-l-naphthol, etc., are suitable.

In effecting the reductive coupling of the present invention it is preferred to utilize a cathode having an overvoltage greater than that of copper and to subject to electrolysis in contact with such cathode a concentrated solution of the defined olefinic compounds in an aqueous electrolyte under mildly alkaline conditions. In effecting the reductive couplings of the present invention, it is desirable that the salt employed should not contain cations which are discharged at substantially lower, i.e., less negative, cathode potentials. It is desirable that the salt employed have a high degree of water solubility to permit use of very concentrated solutions, for concentrated salt solutions dissolve greater amounts of the organic olefinic compounds.

In addition to the foregoing considerations, a number of other factors are important in selecting salts suitable for good results. For example, it is undesirable that the salt cation form an insoluble hydroxide at the operating pH, or that it discharge on the cathode forming an alloy which substantially changes the hydrogen over-voltage and leads to poorer current efiiciencies. The salt anion should not be lost by discharge at the anode with possible formation of byproducts. If a cell containing a separating membrane is used, it is desirable to avoid types of anions which, in contact with hydrogen ions present in the anolyte chamber, would form insoluble acids and clog the pores of the membrane. Alternatively, the use of an ion exchange membrane effectively separates catholyte and anolyte and the use of different anions in the two chambers may minimize any difficulties a particular anion would cause in one of the chambers.

In general, amine and quaternary ammonium salts are suitable for use in the present process. Certain salts of alkali and alkaline earth metals can also be employed to some extent, although they are more subject to interfering discharge at the cathode and the alkaline earth metal salts in general tend to have poor water solubility, making.

their use inadvisable.

The electrolytic reductive couplings of the present invention are conducted in solution in electrolyte, generally in fairly concentrated solution in an aqueous electrolyte. It will be recognized that as used herein an electrolyte is considered aqueous even if the amount of water is small. Many electrolytes can be employed in the present invention but some are less suitable than others. The salts employed, either to provide conductivity or to increase solubility of the reactants have an important bearing on the' electrolysis and will be discussed at length below. The acidity or basicity is also significant, neutral or mildly alkaline solutions generally being preferred. Many olefinic compounds tend to polymerize when electrolyzed in strongly acidic solution, such as solutions of mineral acids,.and it is desirable in such cases to avoid excessive acidity, making it desirable to operate at pHs above about 5 or 6, such as provided by solutions of salts of strong bases. Moreover, the hydrogen ion has a cathode discharge potential of about 1.5 volts, making it desirable to avoid high concentrations of hydrogen ion in the catholyte if the reductive coupling occurs at similar or more negative cathode potentials. The reductive couplings can suitably be conducted at pHs higher than those at which substantial polymerization of olefinic compound occurs, or higher than those at which there is undue generation of hydrogen, for example pI-ls at which more than half the current is expended in discharging hydrogen ions. The pHs referred to are those obtaining in'the bulk of the catholyte solution, such as determinable by a pH meter on a sample of the catholyte removed from the cell. The electrolysis in effect generates acid at the anode and base at the cathode; it will be recognized that in an undivided cell the pH in the immediate vicinity of the cathode may dilfer considerably from that near the anode, particularly if good stirring is not employed. To some extent the effects of acidity can be counteracted by high current density to cause more rapid generation of hydroxyl ions. However, high current densities also require good stirring or turbulence to move the reactants to the cathode.

During electrolysis in a divided cell, alkalinity increases in the catholyte. However, the anolyte becomes acidic.

When a porous diaphragm is used to separate the catholyte from the anolyte, the alkalinity of the catholyte will depend upon the rate of diffusion of acid from the anolyte through the porous barrier. Control of alkalinity in the cathloyte when employing a diaphragm, may thus be realized by purposely leaking acid from the anolyte into the catholyte. It can also be achieved, of course, by extraneous addition to the catholyte of an acid material, e.g., glacial acetic acid, phosphoric acid or ptoluenesulfonic acid. Alkalinity may also be controlled, whether or not a diaphragm is usedin the cell, by employing buffer systems of cations which will maintain the pH :range while not reacting at the reaction conditions.

The phosphonate and phosphinate esters employed in the present invention are in general fairly stable against hydrolysis. However it will be understood that the electrolysis conditions should not be such as to cause an undesired degree of hydrolysis, although in some cases it may be desired to have the ester groups of the products hydrolyzed for a contemplated use.

When a divided cell is employed, it will often be desirable to use an acid as the anolyte, any acid being suitable, particularly dilute mineral acids such as sulfuric or phosphoric acid. Hydrochloric acid can be employed but would have the disadvantage of generating chlorine at the anode, and of being more corrosive with respect to some anode materials. When an acid is employed as anolyte, it is advantageous to use an ion exchange membrane to separate the anolyte from the catholyte. If desired, a salt solution can be used as anolyte, those useful as catholyte also being suitable as anolyte, although there are many other salt solutions suitable for such use.

Materials suitable for constructing the electrolysis cell employed in the present process are well known to those skilled in the art. The electrodes can be of any suitable cathode and anode material. The anode may be of virtually any conductor, although it will usually be advantageous to employ those that are relatively inert or attacked or corroded only slowly by the electrolytes; suitable anodes are, for example, platinum, carbon, gold, nickel, nickel silicide, Duriron, lead and lead-antimony and lead-copper alloys, and alloys of various of the foregoing and other metals.

Any suitable material can be employed as cathode, various metals and alloys being known to the art. It is generally advantageous to employ metals of fairly high hydrogen over-voltage in order to promote current efiiciency and minimize generation of hydrogen during the electrolysis. In general it will be desirable to employ cathodes having over-voltages at least about as great as that of copper, as determined in a 2 N sulfuric acid solution at current density of 1 milliarnp/square centimeter (Carman, Chemical Constitution and Properties of Engineering Materials, Edward Arnold and Co., London, 1949, page 290). Suitable electrode materials include, for example, mercury, cadmium, tin, zinc, bismuth, lead, graphite, aluminum, nickel, etc., in general those of higher over-voltage being preferred. It will be realized that over-voltage can vary with the type of surface and prior history of the metal as well as with other factors; therefore the term over-voltage as used herein with respect to copper as a gauge has reference to the over-voltage under the conditions of use in electrolysis.

Among the salts which can be employed according to the present invention for obtaining the desired concentration of dissolved olefinic compound, the amine and quaternary ammonium salts are generally suitable, especially those of sulfonic and alkyl sulfuric acids.

Such salts can be the saturated aliphatic amine salts or heterocyclic amine salts, e.g., the mono-, dior trialkylamine salts, or the mono-, dior trialkanolamine salts, or the piperidine, pyrrolidine or morpholine salts, e.g., the ethylam'ine, dimethylamine or triisopropylamine salts of various acids, especially various :sulfonic acids. Espeg cially preferred are aliphatic and heterocyclic quaternary ammonium salts, i.e., the tetraalkylammonium or the tetraalkanolammom'um salts or mixed alkyl 'alkanol ammonium salts such as the alkyltrialkanolammonium, the dialkyldialkanolammonium, the alkanotrialkyl'ammonium or the N-heterocyclic N-alkyl ammonium salts of sulfonic or other suitable acids. The saturated aliphatic or heterocyclic quaternary ammonium cations in general have relatively high cathode discharge potentials and readily form salts having suitably high water solubility with anions suitable for use in the electrolytes employed in the present invention. The saturated, aliphatic or heterocyclic quaternary ammonium salts are therefore in general well adapted to dissolving high amounts of olefinic compounds in their aqueous solutions and to effecting reductive couplings of such olefinic compounds. It is understood, of course, that it is undesirable that the ammonium groups contain any reactive groups which might interfere to some extent with the reductive coupling reaction. In this connection it should be noted that aromatic unsaturat'ion as such does not interfere as benzyl substituted ammonium cations can be employed; (as also can aryl sulfonate anions).

Among the anions useful in the electrolytes, the aryl and alkaryl sulfonic acids are especially suitable, for example, salts of the following acids: benzene-sulfonic acid, m-, or p-toluenesulfonic acid, 0-, mor p-ethylbenzenesulfonic acid, o-, mor p-cumenesulfonic acid, o-, mor p-tervamylbenzenesulfonic acid, o-, mor p-hexylbenzene-sulfonic acid, o-Xylene-4-sulfonic acid, p-xylene-Z- sulfonic acid, m-Xylene-4 or S-sulfonic acid, mesitylene-2- sulfonic acid, durene-3-sulfonic acid, pentamethylbenzenesulfonic acid, o-dipropylbenzene 4 sulfonic acid, alphaor beta-naphthalenesulfonic acid, -o-, mor pbiphenylsulfonic acid, and *alpha-methyl-beta-naphthalenesulfonic acid. Alkali metal salts are useful in the present invention with certain limitations, and the alkali metal salts of such sulfonic acids can be employed, i.e., the sodium, potassium, lithium, cesium or rubidium salts such as sodium benzenesulfonate, potassium p-toluenesulfonate, lithium o-biphenylsulfonate, rubidium beta-napththalene'sulfonate, cesium p-ethylbenzenesulfonate, sodium o-xylene-S-sulfonate, or potassium pentamethylbenzenesulfonate. The salts of such sulfonic acids may also be the saturated, aliphatic amine or hetero-cyclic amine salts, e.g., the mono-, dior trialkylamine salts, or the monodior trialkanolamine salts, or the piperidine, pyrrolidine or morpholine salts, e.g., the ethylamine, dimethylamine or triisopropylamine salt of benzenesulfonic acid or of 0-, por m-toluenesulfonic acid; the isopropanolamine, dibutanolamine or triethanolamine salt of o-, por mtoluene sulfonic acid or of o-, por m-biphenylsulfonic acid; the piperidine salt of alphaor beta-naphthalenesulfonic acid or of the cumenesulfonic acids; the pyrrolidine salt of o-, m-, p-amylbenzenesulfonate; the morpholine salt of benzenesulfonic acid, of o-, mor p-toluenesulfoniic acid, or of alphaor beta-napthalenesulfonic acid, etc. In general, the sulfonates of any of the ammonium cations disclosed generically or specifically herein can be employed in the present invention. The aliphatic sulfonates are prepared by reaction of the correspondingly substituted ammonium hydroxide with the sulfonic acid or with an acyl halide thereof. For example, by reaction of a sulfonic acid such as p-toluenesulfonic acid with a tetraalkylammonium hydroxide such as tetraethylammoniurn hydroxide there is obtained tetraethylammonium p-toluenesulfonate, use of which in the presently provided process has been found to give very good results. Other presently useful quaternary ammonium sulfonates are, e.g., tetraethylammoniium o-, or rn-toluenesulfonate or benzenesulfonate; tetraethylammonium o-, mor p-cumenesulfonate or o-, mor p-ethylbenzenesulfonate, tetramethylamm-onium benzene sulfonate, or omor p-toluenesulfonate; N,N-di-methylpiperidinium o-, mor p-toluenesulfonate or o-, mor p-biphenylsulfonate; tetrabutylammonium alphaor beta-naphthalenesulfonate or o-, mor p-toluenesulfonate; tetrapropylammonium o-, mor p-amylbenzenesulfonate or alphaethyl-beta naphthalenesulfonate; tetraethanolammonium o-, mor p-cumenesulfonate or o-, mor p-toluenesulfo nate; tetra-butanolammonium benzenesulfonate or pxylene-3-sulfonate; tetr-apentylammonium o-, mor ptolu-enesulfonate or o-, mor p-hexylbenzenesulfonate, tetrapentanolammon'ium p-cymene-3-sulfonate or benzenesulfonate; methyltriethylamrnonium o-, mor p-toluenesulfonate or mesitylene-Z-sulfonate; trimethylethylammonium o-xylene-4-sulfonate or 0-, mor p-toluenesulfonate; triethylpentylammonium alphaor beta-naphthalene sulfonate or o-, mor p-butylbenzenesulfonate, trimethylethanolammonium benzenesulfonate, or o-, mor p-toluenesulfonate; N,N-di-ethylpipcridinium or N- methyl-pyrrolidinium o-, mor p-hexylbenzenesulfonate or o-, mor p-toluenesulfonate, N,N di-isopropyl or N,N- di-butylmorph'olinium o-, mor p-toluenesulfonate or o-, mor p-biphenylsulfonalte, etc.

The tetraalkylammonium salts of the aryl or alkarylsulfonic acids are generally preferred for use as the salt constituents of the electrolysis solution because the electrolyses in the tetraalkylammonium sulfonates are exclusively electrochemical processes.

Among the ammonium and amine sulfonates useful as electrolytes in the present invention are the alkyl, aralkyl, and heterocyclic amine and ammonium sulfonates, in which ordinarily the individual substituents on the nitrogen atom contain no more than 10 atoms, and usually the amine or ammonium radical contains from 3 to 20 carbon atoms. It will be understood, of course, that diand poly-amines and diand poly-ammonium radicals are operable and included by the terms amine and ammonium. The sulfonate radical can be from aryl, alkyl, alkaryl or aralkyl sulfonic acids of various molecular weights up to for example 20 carbon atoms, preferably about 6 to 20 carbon atoms, and can include one, two or more sulfonate groups.

Another especially suitable class of salts for use in the present invention are the alkylsulfate salts such as methosulfate salts, particularly the amine and quaternary am monium methosulfate salts. Methosulfate salts such as the methyltriethylammonium, tri-n-propyl-methylammonium, triamylmethylammonium, tri-n-butylmethylammoniurn, etc., are very hygroscopic, and the tri-n-butylmethylammonium in particular forms very concentrated aqueous solutions which dissolve large amounts of organic ma-. terials. In general the amine and ammonium cations suitable for use in the alkylsulfate salts are the same as those for the sulfonates.

Various other cations are suitable for use in the present invention, e.g., tetraalkylphosphonium and trialkyl sulfonium cations, particularly as sulfonate salts formed from sulfonic acids as described above, or as methosulfate salts.

In order to improve the solubility of the olefinic compounds in the electrolysis medium it is frequently desirable to include polar organic solvents, preferably solvents which are water miscible such as various alcohols, etc. Acetonitrile and dimethylformamide are particularly suitable as co-solvents.

The bis-phosphonates, bis-phosphinates, bis-phosphine oxides and bis-sulfones are useful as fire retardants for addition to various plastics and resins, such as polyurethanes or polyurethane foam materials, and also as plasticizers in various plastic and resinous coating, wrapping and molding materials, and are also useful as fire resistant hydraulic fluids. The compounds can also be utilized as intermediates in organic reactions and for preparation of other compounds, e.g., the bis-phosphonates and bis-phosphinates can be hydrolyzed by treatment with concentrated acid or other rigorous conditions to obtain the corresponding phosphonic and phosphinic acids, which can, if desired, be further reacted with other compounds.

The following examples are illustrative of the invention.

Example 1 A catholyte was prepared by combining 42.4 grams of a 94.4% by weight concentration of methyltributylammonium, p-toluenesulfonate in water, 7.6 grams water, 50 grams diethyl vinylphosphonate and 40 grams acetonitrile. As anolyte, a 14 ml. solution of 80% by weight tetraethylammonium p-toluenesulfonate in water was employed in an Alundum cup. The anode was platinum and the cathode was 110 ml. mercury. A direct current of 2.3 amperes was passed in for a total of 6.5 ampere-hours with the electrolyte temperature at 30 C. and the cathode voltage at 2.12 volts (vs. saturated calomel electrode). 'During the electrolysis 2.05 grams of acetic acid was added to the catholyte to counteract the hydroxyl ions generated at the cathode. The catholyte was diluted with 250 ml. water and extracted with methylene dichloride. The methylene dichloride extract was washed with water, dried over calcium sulfate, and the methylene dichloride was distilled at atmospheric pressure. The residue was distilled under high vacuum. A 6.3 gram portion of tetra ethyl tetramethylene diphosphonate was taken at 172- 178" C., 0.651.0 mm. and had refractive index Analysis.--Calcd: C, 43.69; H, 8.48; P, 18.79. Found: C, 43.65; 'H, 8.64; P, 17.22. The physical values correspond closely to reported values for the compound.

Example 2 'Diethyl vinylphosphonate was hydrodimerized in a catholyte composed of 50 grams of the phosphonate, 50 grams of an 80% solution of tetraethylammonium p-toluenesulfonate in water, and 40 grams acetonitrile. The anolyte was 14 ml. of a 40% solution of the sulfonate salt. The electrolysis was conducted for a total of 6.21 ampere-hours and 1.5 ml. of acetic acid was added to the catholyte in the course of the electrolysis. The organic material was extracted from the catholyte with organic solvent and the hydrodimer of diethyl vinylphosphonate was isolated by distillation.

Example 3 Diphenylvinylphosph-ine oxide was hydrodimerized in a catholyte containing 30 grams of the phosphine oxide, 50 grams tetraethylammonium p-toluenesulfonate, 30 grams water and 48 grams acetonitrile. As anolyte, a 46% solution of methyltributylammonium p-toluenesulfonate was employed in an Alundum cap. The cathode was 120 ml. mercury, and a very small amount of hydroquinone inhibitor was added to the catholyte. The electrolysis was conducted at 1 ampere at cathode voltage of -2.19 (vs. saturated calomel electrode) for 3.3 amperehours with some hydrogen evolution. The catholyte was diluted with water and extracted with methylene dichloride. The methylene chloride was concentrated and the white crystalline solid hydrodimer precipitated, M.P. 257- 60 C. which is in substantial agreement with the value reported in the literature for tetramethylene-bis-(diphenylphosphine oxide). Analysis.-Calcd: C, 73.33; H, 6.13; P, 13.51. Found: C, 72.18; H, 6.92; P, 12.27. The methylene dichloride solution was chromatographed on activated alumina and elution with methylene dichloride gave a white solid of lower melting point but giving an elemental analysis approximating the theoretical for tetramethylene-bis-(diphenylphosphine oxide).

Example 4 Methyl vinyl sultone was electrolyzed along with N,N- diethylcinnanamide in a catholyte containing 20.3 grams of the amide, 12.7 grams of the sulfone, 50 grams tetraethylammonium p-toluenesulfonate, 110 ml. acetonitrile and 1 ml. water. The anolyte was 12 grams of the sulfonate salt and 8 grams water in an Alundum cup. During the electrolysis 5 ml. of acetic acid was utilized for pH control. The electrolysis was conducted at cathode voltages of 1.68 to -1.88 (vs. saturated calomel electrode) at a current of 1.5 amperes for a total of more than 6 amperes. The catholyte was diluted with water and a solid was obtained by filtration. The solid was recrystallized from water and dried,,M.P. 200201", and infrared analysis indicated absence of the carbonyl grouping. Analysis showed the solid was the hydrodimer of methyl vinyl sultone, tetramethylene bis(methy1 sulfone). Analysis.Calcd: C,33.6'2; H, 6.58; S, 29.93. Found: C, 34.03; H, 6.79; S, 28.89. The aqueous mother liquor was extracted with methylene dichloride and a crude product isolated from the extract by chromatography on activated alumina, and distillation had an infrared spectrum showing the presence of both amide carbonyl (6.15 and sulfone (7.35 and 8.85 groups and an analysis indicating it to be the reductively cross-coupled product of methyl vinyl sulfone and the N,N-diethylamide of cinnam-ic acid, i.e.,

What is claimed is:

1. The method of producing reduced, coupled compounds which comprises subjecting an aqueous salt solution of an olefinic compound selected from the group consisting of alpha,beta-olefinic phosphonates, phosphine oxides and sulfones to electrolysis, the solution containing salt in an amount at least 5% by weight of the water and salt in the solution, by passing an electric current through said solution in contact with a cathode, causing development of the cathode potential required for reductive coupling of the olefinic compound and producing reduced coupled product therefrom, and separating the reduced, coupled product from the solution.

2. The method of claim 1 in which the solution comprises a salt selected from the group consisting of amine and ammonium sulfonates.

3. The method of claim 1 in which the olefinic compound is a l-alkenylphosphonate.

4. The method of claim 1 in which the olefinic compound is a l-alkenyl phosphine oxide.

5. The method of claim 1 in which the olefinic compound is a l-alkenyl sultone.

6. The method of hydrodimerization which comprises subjecting an aqueous solution of olefinic compound selected from the group consisting of alpha-beta-olefinic phosphonates, phosphine oxides and sulfones to electrolysis in contact with a cathode having a hydrogen overvoltage greater than that of copper, causing development of the cathode potential required for hydrodimerization, the solution containing at least about 10% by weight of olefinic compound and having a pH above about 6 and containing at least 5% by weight of salt based on water and salt in the solution, and recovering the hydrodimerized product.

7. The method of claim 6 in which the solution contains a quaternary ammonium aromatic sul-fonate salt.

8. The method of claim 6 in which the olefinic compound is diethyl vinylphosphonate.

9. The method of claim 6 in which the olefinic compound is diphenylvinylphosphine oxide.

10. The method of claim 6 in which the olefinic compound is methyl vinyl sulfone.

11. The method of hydrodimerization which comprises subjecting an aqueous solution of olefinic compound selected from the group consisting of alpha-beta-olefinic phosphonates, phosphine oxides and sulfones to electrolysis in contact with a cathode having a hydrogen overvoltage greater than that of copper, causing development of the cathode potential required for hydrodimerization, the solution containing at least about 10% by weight of olefinic compound and containing quaternary ammonium aromatic sulfonate salt in an amount at least 5% by weight of the water and salt in the solution and recovering the hydrodimerized product.

12. The method of hydrodimerization which comprises subjecting an aqueous solution of olefinic compound selected from the group consisting of alpha-beta-olefinic phosphonates, phosphine oxides and sulfones to electrolysis in contact with a cathode having a hydrogen oivervoltage greater than that of copper, causing development of the cathode potential required for hy-drodimerization, the solution containing at least about 10% by weight of olefinic compound and containing quaternary ammonium aromatic sulfonate salt in an amount at least 5% by weight of the water and salt in the solution, and an organic polar solvent and recovering the hydrodimerized product.

13. The method of claim 12 in which the organic solvent is acetonitrile.

14. The method of producing reduced, coupled compounds which comprises subjecting aqueous salt solution of alpha,beta-olefinic phosphorus compound represented 20 by the formula:

RP (0) X in which R represents a l-alkenyl group, and the Xs are selected from the group consisting of R and OR', and R is a hydrocarbyl radical, to electrolysis, the solution containing salt in an amount at least 5% by Weight of the water and salt in the solution, by passing an electric current through said solution in contact with a cathode, causing development of the cathode poential required for reductive coupling of the alpha,beta-olefinic phosphorus compound and producing reduced coupled product therefrom, and separating the reduced, coupled product from the solution.

References Cited by the Examiner UNITED STATES PATENTS 2,632,729 3/1953 Woodman 204--72 2,726,204 12/1955 Park et al 20472 JOHN H. MACK, Primary Examiner.

MURRAY TILLMAN, WINSTON A. DOUGLAS,

Examiners. 

1. THE METHOD OF PRODUCING REDUCED, COUPLED COMPOUNDS WHICH COMPRISES SUBJECTING AN AQUEOUS SALT SOLUTION OF AN OLEFINIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALPHA, BETA-OLEFINIC PHOSPHONATES, PHOSPHINE OXIDES AND SULFONES TO ELECTROLYSIS, THE SOLUTION CONTAINING SALT IN AN AMOUNT AT LEAST 5% BY WEIGHT OF THE WATER AND SALT IN THE SOLUTION, BY PASSING AN ELECTRIC CURRENT THROUGH SAID SOLUTION IN CONTACT WITH A CATHODE, CAUSING DEVELOPMENT OF THE CATHODE POTENTIAL REQUIRED FOR REDUCTIVE COUPLING OF THE OLEFINIC COMPOUND AND PRODUCING REDUCED COUPLED PRODUCT THEREFROM, AND SEPARATING THE REDUCED, COUPLED PRODUCT FROM THE SOLUTION. 